1. Field of the Invention
The present invention relates to a portable terminal unit such as a mobile telephone or a PDA (Personal Digital Assistant), and specifically to a portable terminal unit configured to have a plurality of housings which are coupled to enable them to be overlapping each other.
2. Description of the Related Art
Conventionally, a folding type mobile telephone 2 shown in FIG. 17 is generally known as a folding type portable telephone including two housings which can be folded. In the folding type mobile telephone 2, a display screen 12 such as LCD (Liquid Crystal Display) which displays output information and a speaker 13 which are provided on an inner face 10 of one housing 4, and an operation section 16 and a microphone 15 are provided on an inner face 14 of another housing 6.
The operation section 16 has a cursor key 18 which for indicating upward, downward, right and left directions so that items displayed on the display screen 12 can be selected, and ten keys 20 for inputting numerals, characters, etc., and other keys for various functions operation section.
In such the folding type mobile telephone 2, a menu selecting screen 22 as shown in FIG. 18 is displayed on the display screen 12 so that a user can select any of its various functions which he or she wants to use.
However, the folding type mobile telephone 2 as shown in FIG. 17 has a problem that while the housing 4 and the housing 6 are folded to be close to each other, the image displayed on the display screen 12 cannot be seen unless the housings 4 and 6 are opened so as to come apart from each other, and the information cannot be browsed in a folded-up state even though information is displayed on the display screen 12.
In order to solve such a problem that it is troublesome and annoying to open the housings 4 and 6 of the folding type mobile telephone 2 in order to browse the display screen 12, there have been proposed some mobile phone sets in which the display screen 12 is directed outward not only in an opened state but also in a folded state or a state corresponding to the folded state.
Examples of the portable terminal unit are the overlapping type portable terminal units disclosed in JP-A-H11-215218, JP-A-2002-141984 and JP-A-2002-135380. These overlapping type portable terminal units are so designed that the display screen provided on one of the housings is directed outward when the two housings that are coupled are opened, which is substantially same manner as the folding type mobile telephone 2 shown in FIG. 17.
However, the design of these overlapping type portable terminal units as disclosed in JP-A-H11-215218, JP-A-2002-141984 and JP-A-2002-135380 are different from the folding type mobile telephone 2 such that one of the housings can be folded and overlapped on another housing by twisting it 180 degree at a coupling section between two housings. Therefore, it is possible to overlap the two housings each other with the display face directing outward.
Disclosed in JP-A-H07-288860 is another type of the conventional overlapping type portable terminal unit. The conventional overlapping type portable terminal unit is so designed that one housing provided with a display screen and another housing provided with an operation section are coupled each other at their end portions, in a state which the display screen and the operation section are directed in the same direction, through a shaft which is provided in a direction of passing through these housings.
This overlapping type portable terminal unit can be opened, by rotating one housing with respect to another housing around the shaft at an angle of 180 degree. Further, the two housings can be kept overlapped each other with the display screen directed outward. Thus, even if a user does not open the two housings, he or she can see an image displayed on the display screen.
In the conventional overlapping type portable terminal units, the display screen can be seen without opening the two housings. However, in the case that a user needs to operate with the operation section, after all, he or she have to rotate one of the two housings at an angle of 180 degree to change the portable terminal unit from the closed state to the opened state.
Operations to change from the closed state to the opened state are somewhat different according to the kind of overlapping type portable terminal unit. However, these operations are simple, and complex operations are not required. Therefore, although the operation for making the opened state from the closed state is always performed in order to make the opened state, addition of any other functions to this opening operation itself is not taken into consideration at all. Therefore, there is a problem that operability of the overlapping type portable terminal unit cannot be improved in this point.
To the contrary, also in the case that the overlapping type portable terminal unit is changed from the opened state to the closed state, addition of any other functions to this closing operation itself is not taken into consideration at all. Therefore, there is a problem that operability of the overlapping type portable terminal unit cannot be improved also in this point.